The present invention relates to grinding machines in general, and more particularly to improvements in the construction and mounting of dressing and/or profiling tools for the working surfaces of grinding wheels in such machines. Still more particularly, the invention relates to improvements in grinding machines wherein a rotary dressing tool is movable between several positions in order to treat (namely, dress and/or shape) different portions of the working surface of a grinding wheel.
It is already known to treat a working surface which exhibits circumferentially extending grooves and/or ridges by resorting to a rotary dressing tool whose orientation with respect to the grinding wheel can be changed so that the tool can treat, in several stages, different portions of the working surface. The material removing surface of the dressing tool need not conform to the working surface. The tool is a relatively thin disk, especially if the working surface of the grinding wheel is formed with narrow and/or deep circumferential grooves. As a rule, the periphery of the dressing tool is caused to travel along one or more paths so as to form an envelope curve corresponding to the desired profile of the working surface of the grinding wheel.
German Offenlegungsschrift No. 2,510,558 discloses a grinding machine wherein the dressing disk can be moved to a plurality of different positions with respect to the grinding wheel. This enables the dressing disk to treat several discrete portions of the working surface, namely, portions which are disposed in different planes and are inclined with respect to each other. To this end, the dressing disk is movable about an axis which extends parallel to the tangential direction of the dressing disk and coincides with the center of curvature of a portion of the usually convex peripheral surface of the dressing disk. Thus, the pivot axis of the disk is immediately adjacent to the working surface because the radius of curvature of the peripheral surface of the dressing disk is relatively small. This enables an attendent to pivot the flat disk-shaped dressing tool in which a way that a point on the radius of this tool engages the working surface while the dressing tool pivots, and such pivoting does not result in undesirable collision of the grinding wheel with other portions of the tool, namely, with portions other than that including the peripheral surface.
A drawback of the just described prior proposal is that the means for mounting and moving the dressing tool are quite complex, bulky and expensive. Moreover, the stability of the dressing tool in each of its positions is unsatisfactory, mainly because it is rather difficult to kinematically define the pivot axis for the tool in such a way that those portions of the tool which are remote from its peripheral surface do not collide with the grinding wheel during movement of the tool between several positions.